In the July 8, 2004, issue of the journal Neuron, the researchers describe the specific group of neurons that are responsible for gasping and what happens to these cells when they are deprived of oxygen. Since gasping resets the normal breathing pattern for babies, the scientists suspect that a malfunction in these respiratory pacemakers is the cellular mechanism that leads to SIDS.
"This paper sets the groundwork for everything that has to do with breathing," says lead author Jan-Marino Ramirez, an associate professor of organismal biology and anatomy. "We've now defined the players in the system."
The study follows a paper published in Nature four years ago in which Ramirez and colleagues showed that the same network of respiratory cells in the brainstem controls different forms of breathing: the sigh, the gasp and normal rhythm.
Shortly after the groundbreaking paper, scientists overturned conventional theory that pacemaker neurons drive the entire network of cells. Researchers found that riluzole, a drug that blocks the cell's sodium channel, could silence pacemaker neurons yet the rhythm of the network remained active.
But, according to Ramirez, riluzole didn't disable all of the pacemakers, which is why the rhythm continued. He found that there are two groups of pacemaker neurons, one of which does not depend on sodium channels to operate, but on calcium channels. Only four out of 172 pacemaker cells were not affected by riluzole.
"You have to have a perfect recording in order to get those cells," Ramirez says. "It's not that these neurons are more powerful, just more elusive."